Abstract: Improving the accuracy of wind power prediction is of great significance to the stable operation of wind farms and the power system. Although the Yaw-control system of the wind turbine generator could make blades adapt to the change of ambient wind direction automatically in theory,the wind direction deviation angle exists generally. Based on the measured data of a wind farm in Jiangxi Province,the distribution characteristics of the wind direction deviation angle and its influence on the output power of wind turbine are analyzed. The results show that the wind direction deviation angle has significant normal distribution and diurnal variation;moreover,when the wind speed is fixed,the larger the wind direction deviation angle is,the smaller the output power is.If the wind direction deviation angle is introduced into the prediction model,the correlation coefficient of wind power prediction can be increased by 0.9%,while the root mean square error and mean absolute error are reduced by 7.9% and 8.6%,respectively. So,it is of positive significance to consider the influence of the wind direction deviation angle in the wind power prediction model.